View cameras are a type of camera used by the professional photographer or by the serious amateur photographer.
View cameras are characterized by several basic components. A camera bed or base is generally arranged to allow it to be telescoped so that the distance between a lens carrying front standard and a film or ground glass carrying rear standard may be lengthened or shortened.
It will be understood that, while the following discussion refers to a vertical dimension and a horizontal dimension, this reference pertains to the attitude of the camera as normally initially set up on a tripod or other support, with the standards lying in parallel planes, with colinear centers that lie on a line that is perpendicular to the long axis of the tripod. With adjustments to the tripod, the standards may be made to lie in virtually any plane desired, at which point the terms "vertical," "horizontal," "side to side," etc., as applied to the motions of the standards, would be arbitrary. For the purposes of the following discussion, and the claims, unless otherwise stated, the description pertains to a camera in the initial set up position, with the standards lying in parallel planes having colinear centers lying on a line that is perpendicular to the long axis of a tripod, or support, or in other words, horizontal. Also, in the following discussion, it will be assumed that the photographer stands behind the camera, facing the subject.
The front standard of the view camera generally consists of a lens carrying board supported by an upstanding arm support and the entire front standard assembly possesses a number of degrees of freedom so that the lens may be adjusted to a wide variety of positions. Typical adjustments of the lens and lens board include an up and down translation, a lateral translation from side to side, a forward and backward tilting adjustment about a pivot axis passing horizontally from side to side through or below the lens board, and a swing or rotary adjustment about a substantially vertical axis running through the lens board.
A similar supporting frame is provided for the rear standard of the camera and many degrees of adjustment are also possible there. The rear section of the camera carries the ground glass plate used in focusing the camera. The film pack or film plate is also carried by the rear standard of the view camera and, after the camera is properly focused, the film is placed in the position previously occupied by the focusing ground glass.
The front standard of the camera is joined to the back standard of the camera by an expandable bellows. The bellows is generally formed of a rubber or plastic-coated fabric or leather and fabric and must, of course, be completely free of light leaks.
The many degrees of adjustment possible with a view camera are useful in a number of different applications. When photographing a subject having a planar face, if the portion of the camera carrying the film is not parallel with the face of the subject to be photographed, a distorted image of that face will be recorded by the camera. For example, tall buildings will appear to taper and slope backwards. To correct these distortions, the film plate must be parallel to the pertinent lines of the subject.
It will be understood that view cameras are normally used by setting them up, initially, with the base aligned parallel to the line of sight and both standards perpendicular to the line of sight. As used below, "line of sight" shall refer to a line from an arbitrary point on the photographic subject, to the lens, as the camera is initially set up with all tilt, shift and swing adjustments at a nominal home position. As the various tilt, swing and shift adjustments are made, the foregoing perpendicularities cease. As the camera is manipulated, the line from the object to the lens may change; the line of sight remains stationary.
Several of the adjustments obtainable with a view camera are as follows. A "down-angle" adjustment (front standard lower than back standard) or "up-angle" adjustment (front standard higher than back standard) permits special photographic effects. For example, the "up-angle" adjustment is often used in photographing buildings. Horizontal and vertical swings (or pivots) of either standard permit an adjustment of the depth of field to sharpen the image of an object nearer to one side of the lens. The rise and fall of the lens carrying board permits the raising or lowering of the lens without changing the attitude (inclination) of either the front or rear standards. Similarly, the lateral, or side shift of the camera front and back permits shifting the lens without changing the attitude of either the front or rear standards.
The invention deals particularly with a type of view camera known as a "field camera." A field camera includes a front and a rear standard, each supported by a frame, which frames in turn translate forward and rearward and are supported by a flat bed. In most cases a field camera's front and rear standards fold into a compact configuration. Known field cameras that incorporate support arms or struts to achieve and control the forward and rearward tilting movement of the front and/or rear standard, and in some cases to allow the folding of compact cameras, have had the capability only of achieving a tilt around a pivot axis located at the base or bed (referred to below as a "base tilt").
When a standard is tilted relative to the substantially horizontal bed after focusing, the standard, which carries the focal point of the ground glass, is swung away from its initial substantially vertical position, requiring refocusing to a degree roughly equal to the distance described by the arc of the tilted standard. To achieve the advantages set out above, a great deal of iterative tilting and refocusing is necessary in order to arrive at the final correct position of the components of the camera, which requires the photographer to move his hands back and forth from one set of controls to the other until the final, precise adjustment is accomplished. It is desirable to provide a tilt, referred to below as a "mid-line tilt," where the standard carrying the focusing ground glass tilts about an axis passing horizontally through the vertical mid-line of the film plate or ground glass and substantially perpendicular to the line of sight.
Another type of view camera, a monorail camera, includes a pair of standards supported by frames which translate forward and backward along a single monorail tube, which tube lies beneath the camera in the center (from left to right relative to the photographer). In monorail cameras, mid-line tilts, or mid-line tilts combined with base tilts are known. However, never has a flat bed field camera, whether of metal or wood, been capable of both mid-line tilts and base tilts in the rear, nor has any field camera which uses struts to facilitate folding and/or base tilt, ever been capable of mid-line tilts in the rear.